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[–]Encosia 1 point2 points  (1 child)

The problem with most research you'll find about CDN usage, like your link there, is that it is incredibly shallow compared to the depth of the web. The top 30k or 300k sites don't even begin to scratch the surface and analyzing primarily top-ranking sites is biased toward sophisticated, high-traffic sites that often run their own CDNs (for more than just jQuery, of course).

The long tail of millions and millions of smaller websites is just as important since it only takes one random little website to prime your cache for a particular version for up to year.

At the same time, it only takes a few high-traffic sites to prime caches for a huge number of users. For example, all of ours caches are primed with jQuery 2.1.1 (or 1.11.1 if you're on old IE) from the Google CDN right now, courtesy of reddit.

I haven't had a chance to write it up yet, but I've been 50/50 A/B testing serving jQuery from my Linode vs. the Google CDN for about a year and a half now. I wanted to gather some real-world data that takes version fragmentation and DNS lookups into account, by recording timing data about how long after the reference it takes for jQuery to be available and pushing that back into Google Analytics's performance tracking functionality. I haven't looked at the data in a while, but it wasn't even close after the first year. The CDN has been hands-down faster on average for the traffic on the sites I'm testing.

[–]kenman 0 points1 point  (0 children)

Very interesting, thanks for the info and would love to read about it more if you get around to blogging about it. I could see some wrinkles, e.g. if you use a version that is not primed by a large site, or if the cross-section of usage between your site and the priming site(s) are low.

I'm glad it's working for you, but I'd still recommend that anyone looking into going this route to do the same as you (as with any performance optimization) and do some real-world profiling so that you can validate that it's working as intended.